[python] fix PprzMessage and don't require msg callback in ivy_msg_interface.py

sw/lib/python/ivy_msg_interface.py

@@ -16,7 +16,7 @@ from pprz_msg.message import PprzMessage
 
 
 class IvyMessagesInterface(object):
-    def __init__(self, callback, init=True, verbose=False, bind_regex='(.*)'):
+    def __init__(self, callback=None, init=True, verbose=False, bind_regex='(.*)'):
         self.callback = callback
         self.ivy_id = 0
         self.verbose = verbose
@@ -47,6 +47,10 @@ class IvyMessagesInterface(object):
         Basically parts/args in string are separated by space, but char array can also contain a space:
         |f,o,o, ,b,a,r| in old format or "foo bar" in new format
         """
+        # return if no callback is set
+        if self.callback is None:
+            return
+
         # first split on array delimiters
         l = re.split('([|\"][^|]*[|\"])', larg[0])
         # strip spaces and filter out emtpy strings

sw/lib/python/pprz_msg/message.py

@@ -130,7 +130,7 @@ class PprzMessage(object):
             if f == name:
                 self._fieldvalues[idx] = value
                 return
-        raise AttributeError("Msg %s has no field of name %s" % (self.name, key))
+        raise AttributeError("Msg %s has no field of name %s" % (self.name, name))
 
     def __str__(self):
         ret = '%s.%s {' % (self.msg_class, self.name)